Conventionally, there are image forming apparatuses such as a Multi-Function Peripheral (hereinafter, referred to as an “MFP”) and a printer. The image forming apparatus is equipped with a fixing device. The fixing device is equipped with a heat roller and a belt. The belt is stretched over a plurality of rollers. The fixing device forms a nip between the heat roller and the belt, and fixes a toner image on an image receiving medium through heat of the heat roller. A predetermined pressurizing force is applied to the inside of a nip width. However, according to the type of image receiving medium, if the image receiving medium in the nip width is bent along the outer peripheral surface of the heat roller, there is a possibility that a wrinkle is generated on the image receiving medium.